Diagnostic Utility of the Albumin-to-Globulin Ratio for Kawasaki Disease in Children Presenting to the Emergency Department

Objectives: Early diagnosis of Kawasaki disease (KD) is essential to prevent coronary artery complications but may be challenging in the emergency department (ED), particularly in patients who do not meet the complete clinical criteria. Although hypoalbuminemia is commonly used as a supportive marker, albumin levels may be influenced by various clinical factors. Therefore, we aimed to evaluate the diagnostic performance of the albumin-to-globulin (A/G) ratio in children with prolonged fever presenting to the ED. Methods: This retrospective case-control study included pediatric patients who presented to a tertiary ED between January 2022 and July 2023. Children diagnosed with KD were compared with febrile controls (fever ≥5 d) diagnosed with other illnesses. The A/G ratio was calculated as albumin/(total protein – albumin). Receiver operating characteristic curve analysis was performed, and areas under the curve (AUCs) were compared using the DeLong test. Results: A total of 134 children with KD and 141 febrile controls were included. Using a cutoff value of ≤1.0, the A/G ratio demonstrated a sensitivity of 82.1% and was associated with an increased likelihood of KD (OR: 5.06; 95% CI: 2.92-8.79). The A/G ratio showed superior discriminatory performance compared with albumin alone (AUC: 0.691 vs. 0.611; P =0.004). No significant differences in the A/G ratio were observed between complete and incomplete KD. Conclusions: An inverted A/G ratio (≤1.0) demonstrated better diagnostic performance than hypoalbuminemia alone and may serve as a simple adjunctive marker for suspected KD in children with prolonged fever presenting to the ED.